Improvement in calipers



tlniii titzt WILLIAM P. HOPKINS, or LAWRENCE, MASSACHUSETTS.

Leners Patent No. 110,657, dana January s, 1871.

IMPROVEMENT IN CAIJPERS.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern.-

Be it known that I, WILLIAM 1?..HOPKrNs, of Lawrence, in the county of Essex and State of Massachusetts, have invented a new and usefulnnprovement in Calipers; and I do hereby declare that the following is a t'ull, clear, and exact descriptiouthereot, which will enable others skilled in the art to make and use the same, reference being had tothe accompanying drawing forming part of this `specification.

This invention relates to improvement in calipers and consists in the arrangementof parts composing a friction-nut'forholding the legs ofthe calipers at any desired angle to each other, as'hereinagter described -Figure 1 is a plan view of my iinprtnfed calipers;

and

Figure 2 is a side view of a part of the adjustingscrew and a section of the nut.

Similar letters of reference indicate corresponding'A gether, and `the spring to force them apart, as heretofore, I reverse the order of the arrangement, using the nut to force them apart andthe spring. to force them together, whereby the calipers, while retaining all their former useful qualities, are made capable of reaching over thick outside rims, anges, or other enlargement, and gauging thinner placesfbeyond, which could not be done as heretofore arranged.

can be readily put on.

To accomplish this the legs are opened against the spring'to pass over the thick place; the nut I is then adjusted to let the points down upon the surfaces oi' the thin place; then the points are forced open to pass back over the thick place, and then let hack against the nut, which holds them the same as when the adjustment was established. Y

Instead of' thearrangement of the -screw E and uut F, as here shown, I may arrange the screw E to screw through one leg against the other, but I prefer this arrangement. v

Alhe friction-nut is composed of two'disks, cf, the one having arecess or socket in one face, iu which is placed a disk of .spring metal or other springing substance, g, and therecess may receive the v other disk falso, to someexteut; bothv disks are connected together by a pin, h,.causing them Ito turn together.

The spring forces the disks in: 'opposite directions against the side walls of the thread of the screw, so as to bind and producethe required friction.

This nut is also applicable to other uses.

The holes in the end of the spring E are drilled, i

previous to temperingV it, so as not to Strain and check the metal, whereby it will be liable to bren-k afterward, and thearrangemeut of the hooks by which it is attached is such that in case itdoes break another AHavin, ;'thns described my invention,

I claim as new and desire to secure by Letters Patent- Theimprovedfriction-nut, consisting of the disks ef, screwy, and the looking-pin h, all combined and arranged substantially as specilied.

l WILLIAM P. HOPKINS. Witnesses A. H. EAMEs, O. K. GURRIER.' 

